A flexible perovskite cell and a preparation method thereof

Abstract

The application provides a flexible perovskite battery and a preparation method thereof, and belongs to the technical field of solar cells, and comprises the following steps: mixing thermoplastic polyurethane and 3-isocyanate propyl triethoxysilane, adding anhydrous N,N-dimethylformamide, and heating to obtain a modified polyurethane solution; mixing formamidinium hydroiodide, iodide, methylammonium salt, the modified polyurethane solution and 4-hydrazinyl benzenesulfonic acid, adding DMSO / DMF solvent, and stirring to obtain a perovskite precursor solution; taking a PET / ITO substrate as a bottom electrode layer; spin coating an isolation layer on the bottom electrode layer; spin coating a SnO2 precursor solution on the isolation layer to obtain an electron transport layer; spin coating the perovskite precursor solution on the electron transport layer to obtain a perovskite layer; spin coating a hole transport layer mixture on the perovskite layer to obtain a hole transport layer; and evaporating a top electrode layer on the hole transport layer to obtain the flexible perovskite battery. The perovskite battery prepared by the application has good flexibility and tensile properties, and the water and oxygen resistance is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a flexible perovskite cell and a preparation method thereof. BACKGROUND

[0002] Perovskite cells have become a research hotspot of new generation photovoltaic technology due to their advantages of wide raw material sources, low preparation cost and flexible process conditions. In particular, flexible perovskite cells have shown broad application prospects in wearable electronic devices, building integrated photovoltaics and portable energy equipment due to their light and thin characteristics and bendable properties.

[0003] However, flexible perovskite cells still face many technical challenges in the process of moving from laboratory research to industrial application. First, perovskite materials themselves have intrinsic instability, and ion vacancy defects exist in their lattices. Under the action of external electric field, light and thermal stress, ion migration is easily induced, causing phase separation and performance degradation. At the same time, metal ions (such as Pb 2+ ) in perovskite are easily oxidized, which accelerates material decomposition and further reduces the operating stability of the device.

[0004] Secondly, flexible application scenarios have higher requirements for the mechanical durability of the device. Perovskite thin films are polycrystalline semiconductor materials, and their grain boundary regions are often weak points in structure. During repeated bending or stretching, microcracks are easily formed and expanded, leading to rapid performance degradation of the device. Therefore, how to endow the perovskite layer with better flexibility and mechanical stability has become the focus of current research. In addition, flexible batteries usually use polymer substrates such as PET / ITO, but such substrates have limited water and oxygen barrier ability. Water and oxygen in the environment can easily penetrate into the perovskite layer, inducing material decomposition and seriously affecting the electrical performance and service life of the device.

[0005] In summary, it is necessary to provide a flexible perovskite cell and a preparation method thereof to solve the problems existing in the prior art. SUMMARY

[0006] Therefore, the present application provides a flexible perovskite cell and a preparation method thereof to improve the flexibility and tensile properties of perovskite thin films and solve the problem of performance degradation caused by water and oxygen penetration.

[0007] To achieve the above-mentioned purpose, the present application provides a flexible perovskite cell and a preparation method thereof, comprising the following steps:

[0008] S1, mixing the thermoplastic polyurethane with 3-isocyanate propyl triethoxysilane, adding anhydrous N, N-dimethylformamide, heating, stirring, to prepare a modified polyurethane solution; mixing formamidine hydroiodide, iodide salt, methylammonium salt, modified polyurethane solution and 4-hydrazinyl benzenesulfonic acid, adding DMSO / DMF solvent, stirring, to prepare a perovskite precursor solution;

[0009] S2, cleaning and activating the PET / ITO substrate to prepare a bottom electrode layer; dropwise adding the SnO2 precursor solution to perform spin coating, heating, cooling and activating to prepare an electron transport layer;

[0010] S3, dropping the perovskite precursor solution on the electron transport layer, spin coating, heating and cooling to prepare a perovskite layer;

[0011] S4, dropping the hole transport layer mixture on the perovskite layer, spin coating, drying to prepare a hole transport layer; evaporating the top electrode layer on the hole transport layer to prepare a flexible perovskite battery.

[0012] The application introduces isocyanate propyl triethoxysilane (IPTS) into thermoplastic polyurethane (TPU), so that the TPU molecular chain has both a flexible main chain and a reactive polar group. The isocyanate group (-NCO) at the end of the IPTS molecule has high reactivity and can react with the amino group (-NH2) in the TPU segment to form a stable urea bond structure (-NH-CO-NH-). The urea bond not only enhances the association ability between polymer segments, but also forms a stable ion-dipole interaction with the free iodine ion (I - ) in the crystal lattice, which has an anchoring function for iodine ions during the film formation process of the perovskite layer, prevents abnormal enrichment of iodine ions, and thus improves the structural stability of the flexible perovskite battery. At the same time, the urea bond plays a key role in stress dispersion and buffering between the flexible main chain when subjected to external stretching or repeated bending, and the amide group in its molecular structure gradually releases and absorbs mechanical energy in the loading-unloading cycle, thereby effectively relieving the stress at the grain boundary and delaying the expansion of cracks, and thus improving the flexibility and tensile properties of the perovskite battery.

[0013] In addition, the flexible intrinsic structure of the TPU main chain can give the perovskite layer good bendability, so that it can still maintain structural integrity under the action of bending external force, avoiding the phenomenon of cracking or delamination, thereby improving the overall flexibility of the battery.

[0014] On this basis, the application further introduces 4-hydrazinyl benzenesulfonic acid molecules into the perovskite precursor solution, and the sulfonic acid group (-SO3H) can form a stable complex with the uncoordinated lead ion (Pb 2+Forming "S-O-Pb" connecting bond, effectively passivating grain boundary and surface defects, the reduction characteristics of hydrazine group can inhibit the oxidation process of lead ions, and improve the intrinsic stability of perovskite layer. At the same time, 4-hydrazine phenyl sulfonic acid can promote perovskite layer to form larger and more uniform grain structure, improve the electron transport efficiency of perovskite layer, and cooperatively modify polyurethane to build "rigid grain-soft interface" structure. When the flexible perovskite battery is subjected to external force, the structure can offset the external force through small reversible deformation, further improving the flexibility of the flexible perovskite battery.

[0015] The bottom electrode layer in the application adopts a flexible PET / ITO substrate, which provides the basis for the bendability of the perovskite battery and realizes the collection and transmission of photo-generated electrons; the electron transport layer can extract electrons and block hole migration, improving the charge separation efficiency; the hole transport layer is used for transporting holes and blocking electron backflow, so that the carriers can be effectively separated and output; the top electrode layer acts as a back electrode responsible for collecting holes and leading out current, and also plays a role in packaging and protecting the device.

[0016] Optionally, a separation layer is also spin-coated between the bottom electrode layer and the electron transport layer, and the separation liquid of the separation layer is prepared by activating polyvinyl carbazole, adding octadecyltrichlorosilane and anhydrous toluene, stirring at a speed of 500-600 rpm for 2-4 h, and constant temperature reaction at 50-60 DEG C for 20-30 min, cooling.

[0017] Optionally, the separation layer is prepared by dropping the separation liquid in the center of the bottom electrode layer, rotating at a speed of 1000-1500 rpm for 10-15 s, then spin-coating at a speed of 3000-3500 rpm for 30-40 s, heating at 95-105 DEG C for 10-15 min, and cooling.

[0018] In the application, polyvinyl carbazole (PVK) is treated by ultraviolet-ozone to introduce hydroxyl active sites, so that condensation reaction occurs between the silane end group (-SiCl3) of octadecyltrichlorosilane (OTS) and the hydroxyl active sites, forming a separation layer containing Si-O-C bond. In the separation layer, the dense coverage of PVK effectively fills the micropore defects of the PET / ITO interface, providing a stable matrix for the ordered arrangement of OTS; OTS is firmly anchored on the PVK film layer through covalent bond, and the long-chain alkyl group is oriented and distributed outward, further reducing the free volume of the film layer and imparting strong hydrophobicity. PVK and OTS form chemical bonding at the interface and synergistically act, not only avoiding the problem of insufficient hydrophobicity of PVK, but also inhibiting the discontinuity of the film layer caused by hydrolysis of OTS, improving the barrier ability of the device to external water and oxygen, and thus enhancing the long-term environmental stability of the flexible perovskite battery. At the same time, PVK as a semiconductor polymer allows efficient transmission of electrons, ensuring the photoelectric conversion efficiency of the flexible perovskite battery.

[0019] Optionally, in the step S1, after adding anhydrous N,N-dimethylformamide, heating at 60-80 DEG C for 1-2h, and stirring at a rotation speed of 800-900 rpm for 6-8h, a modified polyurethane solution is obtained; the iodide salt includes lead iodide and cesium iodide, and the methyl ammonium salt includes methyl ammonium bromide and methyl ammonium chloride; after adding DMSO / DMF solvent, stirring for 1-2h, a perovskite precursor solution is prepared.

[0020] Optionally, in the step S2, the bottom electrode layer is prepared by ultrasonic cleaning a PET / ITO substrate with anhydrous ethanol and deionized water for 30-50 min respectively, drying at 80-90 DEG C, fixing on a glass plate, and irradiating in a UV-ozone cleaning machine for 20-30 min; the electron transport layer is prepared by dropping a SnO2 precursor solution on the center of the bottom electrode layer, spin coating at a rotation speed of 4000-4500 rpm for 20-40 s, heating at 80-95 DEG C for 30-40 min, cooling to room temperature, and irradiating in a UV-ozone cleaning machine for 40-50 min.

[0021] In the application, by ultrasonic cleaning and UV-ozone treatment of the PET / ITO substrate, the impurities on the surface can be effectively removed, the cleanliness and uniformity of the bottom electrode layer are improved, and a good adhesion interface is provided for subsequent film deposition. The electron transport layer is treated by heat treatment process combined with UV-ozone treatment, which can form a dense and uniform transport layer structure, and improve the carrier transport efficiency.

[0022] Optionally, in the step S3, the perovskite layer is prepared by dropping the perovskite precursor solution to the center of the electron transport layer, first spin coating at a rotation speed of 900-1100 rpm for 10-15 s, then spin coating at a rotation speed of 4200-4600 rpm for 20-30 s, dropping chlorobenzene to the center of the electron transport layer, spin coating for 10-20 s, heating at 110-120 DEG C for 10-20 min, and cooling to room temperature.

[0023] In the application, by two-stage spin coating combined with chlorobenzene induced crystallization, the crystalline quality and light absorption capacity of the film layer are improved, and the defect density is reduced, which is beneficial to improve the photoelectric conversion efficiency.

[0024] Optionally, in the step S4, the hole transport layer is prepared by dropping the hole transport layer mixed solution to the center of the perovskite layer, spin coating at a rotation speed of 3500-3800 rpm for 25-30 s, and drying at 30-40 DEG C for 24-30 h; the top electrode layer is prepared by placing a glass plate in a vacuum evaporation film plating device, first evaporating a 10-15 nm thick gold foil at a speed of 0.2-0.4 nm / s, and then evaporating a 70-80 nm thick gold foil at a speed of 2-5 nm / s.

[0025] Optionally, the flexible perovskite battery comprises a bottom electrode layer, an electron transport layer, a perovskite layer, a hole transport layer and a top electrode layer stacked in sequence, the bottom electrode layer is made of a PET / ITO substrate, and the top electrode layer is made of metal evaporation.

[0026] The perovskite layer comprises the following raw materials in parts by weight: formamidinium iodide 85.5-87 parts, lead iodide 250-280 parts, cesium iodide 10-11.5 parts, methylammonium bromide 1.5-2 parts, methylammonium chloride 6-8 parts, modified polyurethane solution 35-38 parts, and 4-hydrazinobenzenesulfonic acid 0.8-1.2 parts; the modified polyurethane solution comprises the following raw materials in parts by weight: thermoplastic polyurethane 18-24 parts, 3-isocyanate propyl triethoxysilane 2-4 parts, and anhydrous N,N-dimethylformamide 1400-1500 parts.

[0027] Optionally, a separation layer is further spin-coated between the bottom electrode layer and the electron transport layer, and the separation layer comprises the following raw materials in parts by weight: polyvinylcarbazole 10-12 parts, octadecyltrichlorosilane 4-6 parts, and anhydrous toluene 860-880 parts.

[0028] Optionally, the electron transport layer comprises the following raw materials in parts by weight: 15wt% SnO2 colloidal dispersion liquid 10-20 parts, and ultrapure water 30-60 parts.

[0029] The hole transport layer comprises the following raw materials in parts by weight: Spiro-OMeTAD powder 70-75 parts, chlorobenzene 1100-1200 parts, tributyl phosphate 26-30 parts, 520g / L TFSI-Li solution 8-10 parts, and 400g / L FK209-Co(III)-TFSI solution 3-5 parts.

[0030] It should be understood that the flexible perovskite battery prepared in the present application is a solar thin film battery.

[0031] The above technical scheme of the present application at least has the following beneficial effects:

[0032] In the present application, isocyanate propyl triethoxysilane (IPTS) is introduced into thermoplastic polyurethane (TPU) to construct a urea bond structure in the TPU segment, anchor free iodine ions in the perovskite, prevent migration and abnormal enrichment of iodine ions, and improve the structural stability of the battery. The urea bond connection structure can disperse stress and relieve crack propagation, and improve the flexibility and tensile properties of the flexible perovskite battery. The flexible properties of the TPU backbone endow the light absorption layer with good bendability, avoid breaking or delamination, and enhance the overall flexibility and stability.

[0033] The application also introduces 4-hydrazinobenzenesulfonic acid molecules into the perovskite precursor solution, uses the sulfonic acid group to form a “S-O-Pb” bond with lead ions, realizes the passivation of grain boundaries and surface defects, and simultaneously inhibits lead oxidation through the hydrazine group to improve the stability of the material. The 4-hydrazinobenzenesulfonic acid can promote the increase and uniform distribution of crystal grains, and cooperates with the modified polyurethane to construct a “rigid crystal grain-flexible interface” structure, further improving the flexibility of the flexible perovskite battery. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of the flexible perovskite battery in the embodiment of the application.

[0035] Figure 2 It is an SEM diagram of the perovskite layer in Example 1 of the application.

[0036] Figure 3 It is an SEM diagram of the perovskite layer in Comparative Example 3 of the application.

[0037] In the figure:

[0038] 1, bottom electrode layer; 2, isolation layer; 3, electron transport layer; 4, perovskite layer; 5, hole transport layer; 6, top electrode layer. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the embodiments of the application more clear, the technical scheme of the embodiments of the application will be described below in combination with the embodiments of the application. The described embodiments are part of the embodiments of the application, and all other embodiments obtained by those skilled in the art based on the described embodiments of the application belong to the scope of protection of the application.

[0040] Preparation: a PET / ITO film with a size of 750mm×750mm was selected as a substrate, the PET / ITO substrate was ultrasonically cleaned with anhydrous ethanol and deionized water for 30min respectively, impurities on the surface of the PET / ITO substrate were cleaned away, and the substrate was dried at 80℃, adhered and fixed on a glass plate using a polyimide (PI) tape, and placed in an ultraviolet-ozone cleaning machine for irradiation for 30min to obtain a bottom electrode layer.

[0041] Example 1

[0042] 10g of polyvinylcarbazole was irradiated in an ultraviolet-ozone cleaning machine for 30min, 4g of octadecyltrichlorosilane and 860g of anhydrous toluene were added, sealed, and stirred at a speed of 600rpm under N2 protection in the dark for 2h, heated to 50℃ for reaction for 20min, and cooled to room temperature to obtain an isolation liquid.

[0043] A SnO2 precursor solution was prepared by mixing 10 g of a 15 wt% SnO2 colloidal dispersion and 30 g of ultrapure water, stirring with a magnetic stirrer for 1.5 h.

[0044] A modified polyurethane solution was prepared by mixing 18 g of a thermoplastic polyurethane (TPU) and 2 g of 3-isocyanatopropyltriethoxysilane, adding 1400 g of anhydrous N,N-dimethylformamide (DMF), heating at 60°C for 1.5 h, and stirring at a speed of 800 rpm for 7 h.

[0045] A perovskite precursor solution was prepared by mixing 85.5 g of formamidinium iodide (FAI), 250 g of lead iodide (PbI2), 10 g of cesium iodide (CsI), 1.5 g of methylammonium bromide (MABr), 6 g of methylammonium chloride (MACI), 35 g of the modified polyurethane solution, and 0.8 g of 4-hydrazinobenzenesulfonic acid, stirring, adding 500 mL of a DMSO / DMF solvent in a volume ratio of 1:4, stirring for 1 h until the solution was clear, and then stirring.

[0046] A hole transport layer mixture was prepared by mixing 70 g of Spiro-OMeTAD powder, 1100 g of chlorobenzene, 26 g of tributylphosphite (T-BP), 8 g of a TFSI-Li solution with a concentration of 520 g / L, and 3 g of a FK209-Co(III)-TFSI solution with a concentration of 400 g / L, and stirring until uniform.

[0047] A glass plate was fixed to a spin coater chuck, 100 μL of a spacer solution was dropped onto the bottom electrode layer, the plate was rotated at a speed of 1000 rpm for 12 s, then it was spin-coated at a speed of 3000 rpm for 35 s, the sample was placed on a heating stage at 95°C for 15 min, and then it was cooled to room temperature to form a spacer layer.

[0048] A glass plate was fixed to a spin coater chuck, 150 mL of the SnO2 precursor solution was dropped onto the center of the spacer layer, the spin coater was started and the plate was spin-coated at a speed of 4000 rpm for 25 s, the plate was placed on a heating stage at 80°C for 40 min, then it was cooled to room temperature, and then it was irradiated in a UV-ozone cleaner for 40 min to prepare an electron transport layer.

[0049] A glass plate was fixed to a spin coater chuck, 60 mL of the perovskite precursor solution was dropped onto the center of the electron transport layer, the plate was spin-coated at a speed of 1000 rpm for 12 s, then it was spin-coated at a speed of 4200 rpm for 30 s, 140 mL of chlorobenzene was dropped onto the center of the electron transport layer and spin-coated for another 10 s, after spin-coating was completed, the glass plate was placed on a heating stage at 110°C for 15 min, then the sample was removed from the heating stage and cooled to room temperature to prepare a perovskite layer.

[0050] The glass plate was fixed on the spin coater chuck, 60 mL of hole transport layer mixed solution was dropped on the center of perovskite layer, and spin coating was performed at a speed of 3600 rpm for 25 s. The sample was placed in a drying oven at 40℃ for 24 h to obtain the hole transport layer.

[0051] The glass plate was placed in the evaporation chamber of the vacuum evaporation coating equipment. First, a 15 nm thick gold foil was evaporated at a speed of 0.2 nm / s. Then the evaporation rate was slowly increased to 3 nm / s and a 90 nm thick gold foil was uniformly evaporated to obtain the top electrode layer. Thus, a flexible perovskite battery was prepared.

[0052] Example 2

[0053] 11 g of polyvinyl carbazole was irradiated in a UV-ozone cleaner for 30 min, 5 g of octadecyltrichlorosilane and 870 g of anhydrous toluene were added, sealed, and stirred at 550 rpm under N2 protection for 3 h in the dark. The reaction was heated to 55℃ for 30 min and then cooled to room temperature to obtain the isolation solution.

[0054] 15 g of 15 wt% SnO2 colloidal dispersion and 45 g of ultrapure water were mixed and stirred with a magnetic stirrer for 2 h to obtain the SnO2 precursor solution.

[0055] 20 g of thermoplastic polyurethane (TPU) was mixed with 3 g of 3-isocyanate propyl triethoxysilane, 1450 g of anhydrous N, N-dimethylformamide (DMF) was added, and the mixture was heated at 80℃ for 1.5 h and stirred at a speed of 800 rpm for 6 h to obtain the modified polyurethane solution.

[0056] 86.5 g of formamidinium hydriodide (FAI), 260 g of lead iodide (PbI2), 11 g of cesium iodide (CsI), 1.8 g of methylammonium bromide (MABr), 7 g of methylammonium chloride (MACl), 36 g of modified polyurethane solution, and 1 g of 4-hydrazinobenzenesulfonic acid were mixed and stirred, 500 mL of DMSO / DMF solvent with a volume ratio of 1:4 was added, and the mixture was stirred for 2 h until the solution was clear to obtain the perovskite precursor solution.

[0057] 73 g of Spiro-OMeTAD powder, 1150 g of chlorobenzene, 28 g of tributyl phosphate (T-BP), 9 g of TFSI-Li solution with a concentration of 520 g / L, and 4 g of FK209-Co (III)-TFSI solution with a concentration of 400 g / L were mixed and stirred uniformly to obtain the hole transport layer mixed solution.

[0058] The glass plate was fixed on the spin coater chuck, 100 μL of the isolation solution was dropped on the bottom electrode layer, and spin coating was performed at a speed of 1100 rpm for 12 s. Then, spin coating was performed at a speed of 3500 rpm for 30 s. The sample was placed on a heating stage at 105℃ for 10 min and then cooled to room temperature to form the isolation layer.

[0059] The glass plate was fixed on the chuck of the spin coater, 150 mL of SnO2 precursor solution was dropped on the center of the isolation layer, the spin coater was started, and spin coating was performed at a speed of 4000 rpm for 30 s. The glass plate was placed on a heating table at 80 °C for 40 min, and then cooled to room temperature. The glass plate was placed in a UV-ozone cleaner and irradiated for 50 min to obtain the electron transport layer.

[0060] The glass plate was fixed on the chuck of the spin coater, 60 mL of perovskite precursor solution was dropped on the center of the electron transport layer, and spin coating was performed at a speed of 1100 rpm for 10 s and then at a speed of 4400 rpm for 25 s. 140 mL of chlorobenzene was dropped on the center of the electron transport layer and spin coating was continued for 15 s. After spin coating was completed, the glass plate was placed on a heating table at 120 °C for 15 min, and then the sample was removed from the heating table and cooled to room temperature to obtain the perovskite layer.

[0061] The glass plate was fixed on the chuck of the spin coater, 60 mL of hole transport layer mixture was dropped on the center of the perovskite layer, and spin coating was performed at a speed of 3800 rpm for 25 s. The glass plate was placed in a drying oven at 40 °C for 26 h to obtain the hole transport layer.

[0062] The glass plate was placed in the evaporation chamber of a vacuum evaporation film coating device. First, a 12 nm thick gold foil was evaporated at a speed of 0.4 nm / s. Then, the evaporation speed was slowly increased to 4 nm / s, and a 80 nm thick gold foil was uniformly evaporated at this speed to obtain the top electrode layer. Thus, a flexible perovskite battery was prepared.

[0063] Example 3

[0064] 12 g of polyvinylcarbazole was irradiated in a UV-ozone cleaner for 25 min, 6 g of octadecyltrichlorosilane and 880 g of anhydrous toluene were added, and the mixture was sealed and stirred at a speed of 600 rpm under N2 protection in the dark for 4 h. The mixture was heated to 60 °C and reacted for 25 min, and then cooled to room temperature to obtain the isolation solution.

[0065] 20 g of 15 wt% SnO2 colloidal dispersion and 60 g of ultrapure water were mixed, and the mixture was stirred using a magnetic stirrer for 2 h to obtain the SnO2 precursor solution.

[0066] 24 g of thermoplastic polyurethane (TPU) was mixed with 4 g of 3-isocyanate propyl triethoxysilane, 1500 g of anhydrous N, N-dimethylformamide (DMF) was added, and the mixture was heated at 70 °C for 2 h and stirred at a speed of 800 rpm for 8 h to obtain the modified polyurethane solution.

[0067] A perovskite precursor solution was prepared by mixing 87 g of formamidinium hydriodide (FAI), 280 g of lead iodide (PbI2), 11.5 g of cesium iodide (CsI), 2 g of methylammonium bromide (MABr), 8 g of methylammonium chloride (MACI), 38 g of a modified polyurethane solution, and 1.2 g of 4-hydrazinobenzenesulfonic acid under stirring, adding 500 mL of a DMSO / DMF solvent in a volume ratio of 1:4, and stirring for 1.5 h until the solution was clear.

[0068] A hole transport layer mixture was prepared by mixing 75 g of Spiro-OMeTAD powder, 1200 g of chlorobenzene, 29 g of tributyl phosphate (T-BP), 10 g of a TFSI-Li solution with a concentration of 520 g / L, and 5 g of a FK209-Co (III)-TFSI solution with a concentration of 400 g / L, and stirring until uniform.

[0069] A glass plate was fixed to a spin coater chuck, 100 μL of a spacer solution was dropped on the bottom electrode layer, and the sample was rotated at a speed of 1500 rpm for 14 s, followed by rotation at a speed of 3500 rpm for 30 s. The sample was then placed on a heating stage at 95°C and heated for 15 min, and then cooled to room temperature to form a spacer layer.

[0070] The glass plate was fixed to a spin coater chuck, 150 mL of a SnO2 precursor solution was dropped on the center of the spacer layer, and the spin coater was started to spin at a speed of 4000 rpm for 35 s. The sample was then placed on a heating stage at 95°C and heated for 35 min, and then cooled to room temperature. The sample was then placed in an ultraviolet-ozone cleaner and irradiated for 45 min to prepare an electron transport layer.

[0071] The glass plate was fixed to a spin coater chuck, 60 mL of a perovskite precursor solution was dropped on the center of the electron transport layer, and the sample was first spun at a speed of 1000 rpm for 12 s, and then spun at a speed of 4400 rpm for 25 s. 140 mL of chlorobenzene was then dropped on the center of the electron transport layer and the sample was spun for another 20 s. After the spin coating was completed, the glass plate was placed on a heating stage at 110°C and heated for 10 min. The sample was then removed from the heating stage and cooled to room temperature to prepare a perovskite layer.

[0072] The glass plate was fixed to a spin coater chuck, 60 mL of a hole transport layer mixture was dropped on the center of the perovskite layer, and the sample was spun at a speed of 3600 rpm for 25 s. The sample was then placed in a drying oven at 30°C and dried for 30 h to prepare a hole transport layer.

[0073] The glass plate was placed in an evaporation chamber of a vacuum evaporation film plating device. A 12 nm thick gold foil was first evaporated at a speed of 0.4 nm / s, and then the evaporation speed was slowly increased to 4 nm / s and maintained at this speed to evaporate a 80 nm thick gold foil to obtain a top electrode layer. A flexible perovskite battery was thus prepared.

[0074] Example 4

[0075] SnO2 precursor solution was prepared by mixing 10 g of 15 wt% SnO2 colloidal dispersion and 30 g of ultrapure water, stirring for 1.5 h using a magnetic stirrer.

[0076] Modified polyurethane solution was prepared by mixing 18 g of thermoplastic polyurethane (TPU) and 2 g of 3-isocyanatopropyltriethoxysilane, adding 1400 g of anhydrous N,N-dimethylformamide (DMF), heating at 60 °C for 1.5 h, and stirring at 800 rpm for 7 h.

[0077] Perovskite precursor solution was prepared by mixing 85.5 g of formamidinium iodide (FAI), 250 g of lead iodide (PbI2), 10 g of cesium iodide (CsI), 1.5 g of methylammonium bromide (MABr), 6 g of methylammonium chloride (MACI), 35 g of modified polyurethane solution, and 0.8 g of 4-hydrazinobenzenesulfonic acid, stirring, adding 500 mL of DMSO / DMF solvent in a volume ratio of 1:4, stirring for 1 h until the solution was clear.

[0078] Hole transport layer mixture was prepared by mixing 70 g of Spiro-OMeTAD powder, 1100 g of chlorobenzene, 26 g of tributylphosphite (T-BP), 8 g of TFSI-Li solution with a concentration of 520 g / L, and 3 g of FK209-Co(III)-TFSI solution with a concentration of 400 g / L, and stirring until uniform.

[0079] The electron transport layer was prepared by fixing a glass plate to a spin coater chuck, dropping 150 mL of SnO2 precursor solution onto the center of the bottom electrode layer, starting the spin coater at a speed of 4000 rpm for 25 s, placing it on a heating stage at 80 °C for 40 min, then cooling to room temperature, and placing it in a UV-ozone cleaner for 40 min.

[0080] The perovskite layer was prepared by fixing a glass plate to a spin coater chuck, dropping 60 mL of perovskite precursor solution onto the center of the electron transport layer, first spinning at a speed of 1000 rpm for 12 s, then spinning at a speed of 4200 rpm for 30 s, dropping 140 mL of chlorobenzene onto the center of the electron transport layer and continuing to spin for 10 s, and then placing the glass plate on a heating stage at 110 °C for 15 min before removing the sample from the heating stage and cooling it to room temperature.

[0081] The hole transport layer was prepared by fixing a glass plate to a spin coater chuck, dropping 60 mL of hole transport layer mixture onto the center of the perovskite layer, spinning at a speed of 3600 rpm for 25 s, and placing it in a drying oven at 40 °C for 24 h.

[0082] The glass plate was placed in the evaporation chamber of the vacuum evaporation coating equipment, and a 15 nm thick gold foil was first evaporated at a speed of 0.2 nm / s, and then the evaporation rate was slowly increased to 3 nm / s and kept at a uniform speed to evaporate a 90 nm thick gold foil to obtain a top electrode layer, and a flexible perovskite battery was prepared.

[0083] Example 5

[0084] 15 g of 15 wt% SnO2 colloidal dispersion and 45 g of ultrapure water were mixed, and stirred for 2 h using a magnetic stirrer to prepare a SnO2 precursor solution.

[0085] 20 g of thermoplastic polyurethane (TPU) was mixed with 3 g of 3-isocyanate propyl triethoxysilane, 1450 g of anhydrous N,N-dimethylformamide (DMF) was added, heated at 80°C for 1.5 h, and stirred at 800 rpm for 6 h to obtain a modified polyurethane solution.

[0086] 86.5 g of formamidinium hydriodide (FAI), 260 g of lead iodide (PbI2), 11 g of cesium iodide (CsI), 1.8 g of methylammonium bromide (MABr), 7 g of methylammonium chloride (MACl), 36 g of modified polyurethane solution, and 1 g of 4-hydrazinobenzenesulfonic acid were mixed and stirred, 500 mL of DMSO / DMF solvent with a volume ratio of 1:4 was added, and stirred for 2 h until the solution was clear to prepare a perovskite precursor solution.

[0087] 73 g of Spiro-OMeTAD powder, 1150 g of chlorobenzene, 28 g of tributyl phosphate (T-BP), 9 g of TFSI-Li solution with a concentration of 520 g / L, and 4 g of FK209-Co(III)-TFSI solution with a concentration of 400 g / L were mixed and stirred uniformly to prepare a hole transport layer mixture.

[0088] The glass plate was fixed to the chuck of the spin coater, 150 mL of the SnO2 precursor solution was dropped onto the center of the bottom electrode layer, the spin coater was started, and the glass plate was spun at a speed of 4000 rpm for 30 s, then placed on a heating platform at 80°C for 40 min, then cooled to room temperature, and then placed in a UV-ozone cleaner for irradiation for 50 min to prepare an electron transport layer.

[0089] The glass plate was fixed to the chuck of the spin coater, 60 mL of the perovskite precursor solution was dropped onto the center of the electron transport layer, and the glass plate was first spun at a speed of 1100 rpm for 10 s, then spun at a speed of 4400 rpm for 25 s, 140 mL of chlorobenzene was dropped onto the center of the electron transport layer and continued to spin for 15 s, and after the spin coating was completed, the glass plate was placed on a heating platform at 120°C for 15 min, then removed from the heating platform and cooled to room temperature to prepare a perovskite layer.

[0090] The glass plate was fixed on the chuck of the spin coater, 60 mL of the perovskite precursor solution was dropped on the center of the perovskite layer, and the glass plate was rotated at a speed of 3800 rpm for 25 s. The glass plate was then placed in a drying oven at 40°C for 26 h to obtain the hole transport layer.

[0091] The glass plate was placed in the evaporation chamber of the vacuum evaporation coating device. First, a 12 nm thick gold foil was evaporated at a speed of 0.4 nm / s. Then, the evaporation speed was slowly increased to 4 nm / s, and a 80 nm thick gold foil was uniformly evaporated to obtain the top electrode layer. Thus, a flexible perovskite battery was prepared.

[0092] Example 6

[0093] 20 g of 15 wt% SnO2 colloidal dispersion and 60 g of ultrapure water were mixed, and the mixture was stirred using a magnetic stirrer for 2 h to obtain a SnO2 precursor solution.

[0094] 24 g of thermoplastic polyurethane (TPU) and 4 g of 3-isocyanate propyl triethoxysilane were mixed, 1500 g of anhydrous N, N-dimethylformamide (DMF) was added, and the mixture was heated at 70°C for 2 h and stirred at a speed of 800 rpm for 8 h to obtain a modified polyurethane solution.

[0095] 87 g of formamidinium iodide (FAI), 280 g of lead iodide (PbI2), 11.5 g of cesium iodide (CsI), 2 g of methylammonium bromide (MABr), 8 g of methylammonium chloride (MACl), 38 g of the modified polyurethane solution, and 1.2 g of 4-hydrazinobenzenesulfonic acid were mixed and stirred, 500 mL of DMSO / DMF solvent with a volume ratio of 1:4 was added, and the mixture was stirred for 1.5 h until the solution was clear to obtain a perovskite precursor solution.

[0096] 75 g of Spiro-OMeTAD powder, 1200 g of chlorobenzene, 29 g of tributyl phosphate (T-BP), 10 g of TFSI-Li solution with a concentration of 520 g / L, and 5 g of FK209-Co (III)-TFSI solution with a concentration of 400 g / L were mixed and stirred uniformly to obtain a hole transport layer mixture.

[0097] The glass plate was fixed on the chuck of the spin coater, 150 mL of the SnO2 precursor solution was dropped on the center of the bottom electrode layer, and the glass plate was rotated at a speed of 4000 rpm for 35 s. The glass plate was then placed on a heating platform at 95°C for 35 min, and then cooled to room temperature. Finally, the glass plate was placed in a UV-ozone cleaner and irradiated for 45 min to obtain an electron transport layer.

[0098] The glass plate is fixed to the chuck of the spin coater, 60 mL of perovskite precursor solution is dropped to the center of the electron transport layer, and then spin coating is carried out at a speed of 1000 rpm for 12 s, and then spin coating is carried out at a speed of 4400 rpm for 25 s; 140 mL of chlorobenzene is dropped to the center of the electron transport layer and spin coating is continued for 20 s; after spin coating is completed, the glass plate is placed on a heating table at 110 DEG C and heated for 10 min, then the sample is taken off from the heating table and cooled to room temperature, and a perovskite layer is prepared.

[0099] The glass plate is fixed to the chuck of the spin coater, 60 mL of perovskite precursor solution is dropped to the center of the electron transport layer, and then spin coating is carried out at a speed of 1000 rpm for 12 s, and then spin coating is carried out at a speed of 4400 rpm for 25 s; 140 mL of chlorobenzene is dropped to the center of the electron transport layer and spin coating is continued for 20 s; after spin coating is completed, the glass plate is placed on a heating table at 110 DEG C and heated for 10 min, then the sample is taken off from the heating table and cooled to room temperature, and a perovskite layer is prepared.

[0100] The glass plate is placed in the evaporation chamber of the vacuum evaporation film coating equipment, first evaporates a 12 nm thick gold foil at a speed of 0.4 nm / s, then slowly increases the evaporation rate to 4 nm / s and keeps the gold foil at a uniform speed of 80 nm thick, to obtain a top electrode layer, and a flexible perovskite battery is prepared.

[0101] The present application also carries out comparative examples and related tests.

[0102] Comparative Example 1

[0103] The difference between Example 4 is only that the modified polyurethane solution is not added to the perovskite precursor solution, and the other components and preparation steps are completely consistent, and a flexible perovskite battery is prepared.

[0104] Comparative Example 2

[0105] The difference between Example 5 is only that 3-isocyanate propyl triethoxysilane is not added to the modified polyurethane solution, and the other components and preparation steps are completely consistent, and a flexible perovskite battery is prepared.

[0106] Comparative Example 3

[0107] The difference between Example 1 is only that 4-hydrazine phenyl sulfonic acid is not added to the perovskite precursor solution, and the other components and preparation steps are completely consistent, and a flexible perovskite battery is prepared.

[0108] The flexible perovskite batteries prepared in Examples 1-6 and Comparative Examples 1-3 are tested for performance. The basic photoelectric conversion efficiency PCE0 of the flexible perovskite battery is tested according to the standard DB35T 2143-2023 "Perovskite Solar Cell Conversion Efficiency Evaluation Procedure".

[0109] The flexible test method of the flexible perovskite battery: the flexible perovskite battery is bent into an arc shape with a radius of 100 mm, and after 5000 times of repeated bending, the photoelectric conversion efficiency PCE1 of the flexible perovskite battery is tested.

[0110] The mechanical stretching performance test method of the flexible perovskite battery: after the flexible perovskite battery is stretched by 15%, the light-to-electricity conversion efficiency PCE2 of the flexible perovskite battery is tested after the stretching force is removed and the flexible perovskite battery is automatically restored.

[0111] The water-oxygen resistance test method of the flexible perovskite battery: after the flexible perovskite battery is placed in an environment with a temperature of 25 DEG C and a relative humidity of 50% for 800h, the light-to-electricity conversion efficiency PCE3 of the flexible perovskite battery is tested.

[0112] The related performance test results are shown in Table 1.

[0113] Table 1

[0114]

[0115] In Table 1, the retention rate calculation formula of the flexible perovskite battery is: η i = PCE i / PCE 0 x 100, wherein i = 1, 2, 3. i i

[0116] As shown in Table 1, the flexible perovskite battery prepared in Examples 1-3 includes a bottom electrode layer 1, a separation layer 2, an electron transport layer 3, a perovskite layer 4, a hole transport layer 5 and a top electrode layer 6 which are sequentially stacked. Figure 1

[0117] It can be known from Table 1 that, compared with Examples 4-6 without introducing the separation layer, Examples 1-3 have higher water-oxygen resistance after introducing the separation layer, which indicates that the separation layer helps to block the erosion of water and oxygen to the flexible perovskite battery, thereby improving the service life of the flexible perovskite battery.

[0118] It can be known from Table 1 that, compared with Example 4, the perovskite layer of Comparative Example 1 lacks a flexible buffer structure due to the absence of the modified polyurethane solution, which leads to an intensified grain boundary stress and lower overall flexibility and tensile resistance than Example 4.

[0119] It can be known from Table 1 that, compared with Example 5, the polyurethane solution used in Comparative Example 2 is not modified, which leads to a decrease in flexibility and tensile resistance, and a more obvious decrease in tensile retention rate, which indicates that the unmodified polyurethane is difficult to form an effective buffer structure in the film, and the structural stability is weakened.

[0120] Figure 2 It is an SEM image of the perovskite layer in Example 1 of the present application, wherein the size of the crystal grains is large, and the crystal grains are uniformly distributed; Figure 3 ​​​The SEM image of the perovskite layer in the present application comparative example 3, wherein the grain size is small and the grain distribution is uneven. As can be seen from Table 1, compared with example 1, comparative example 3 does not introduce 4-hydrazinobenzenesulfonic acid in the perovskite precursor solution, resulting in a decrease in the grain size and uneven distribution of the grains in the perovskite layer, which is prone to stress concentration, thereby reducing the flexibility and tensile resistance of the perovskite layer.

[0121] The above is the preferred embodiment of the present application, and those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A method for preparing a flexible perovskite solar cell, characterized in that, Includes the following steps: S1. A modified polyurethane solution is prepared by mixing thermoplastic polyurethane with 3-isocyanate-propyltriethoxysilane, adding anhydrous N,N-dimethylformamide, heating and stirring. A modified polyurethane solution is prepared by mixing formamidinium hydroiodate, iodide, methylammonium salt, modified polyurethane solution and 4-hydrazinobenzenesulfonic acid, adding DMSO / DMF solvent and stirring. S2. Clean and activate the PET / ITO substrate to obtain the bottom electrode layer; add SnO2 precursor solution dropwise for spin coating, heat, cool, and activate to obtain the electron transport layer. S3. Drop the perovskite precursor solution onto the electron transport layer, spin-coat, heat, and cool to obtain the perovskite layer. S4. Drop the hole transport layer mixture onto the perovskite layer, spin-coat, and dry to obtain the hole transport layer. Flexible perovskite solar cells were fabricated by depositing a top electrode layer on the hole transport layer.

2. The method for preparing a flexible perovskite solar cell according to claim 1, characterized in that, An isolation layer is also spin-coated between the bottom electrode layer and the electron transport layer. The isolation solution of the isolation layer is prepared by activating polyvinylcarbazole, adding octadecyltrichlorosilane and anhydrous toluene, stirring at 500-600 rpm for 2-4 hours, reacting at 50-60°C for 20-30 minutes, and then cooling.

3. The method for preparing a flexible perovskite solar cell according to claim 2, characterized in that, The insulating layer is prepared by dripping an insulating liquid into the center of the bottom electrode layer, rotating it at 1000-1500 rpm for 10-15 seconds, then spin-coating it at 3000-3500 rpm for 30-40 seconds, heating it at 95-105°C for 10-15 minutes, and then cooling it.

4. The method for preparing a flexible perovskite solar cell according to claim 1, characterized in that, In step S1, after adding anhydrous N,N-dimethylformamide, the mixture is heated at 60-80°C for 1-2 hours and stirred at 800-900 rpm for 6-8 hours to obtain a modified polyurethane solution. The iodide salts include lead iodide and cesium iodide, and the methylammonium salts include methylammonium bromide and methylammonium chloride; After adding DMSO / DMF solvent, stir for 1-2 hours to obtain a perovskite precursor solution.

5. The method for preparing a flexible perovskite solar cell according to claim 1, characterized in that, In step S2, the bottom electrode layer is prepared by ultrasonically cleaning the PET / ITO substrate with anhydrous ethanol and deionized water for 30-50 minutes, drying it at 80-90°C, fixing it on a glass plate, and irradiating it in an ultraviolet-ozone cleaner for 20-30 minutes. The electron transport layer is prepared by adding a SnO2 precursor solution to the center of the bottom electrode layer, spin-coating at 4000-4500 rpm for 20-40 seconds, heating at 80-95°C for 30-40 minutes, cooling to room temperature, and irradiating with an ultraviolet-ozone cleaner for 40-50 minutes.

6. The method for preparing a flexible perovskite solar cell according to claim 1, characterized in that, In step S3, the perovskite layer is prepared by dropping a perovskite precursor solution onto the center of the electron transport layer, first spin-coating at 900-1100 rpm for 10-15 s, then spin-coating at 4200-4600 rpm for 20-30 s, dropping chlorobenzene onto the center of the electron transport layer, spin-coating for 10-20 s, heating at 110-120℃ for 10-20 min, and cooling to room temperature.

7. The method for preparing a flexible perovskite solar cell according to claim 1, characterized in that, In step S4, the hole transport layer is obtained by adding a hole transport layer mixture to the center of the perovskite layer, spin-coating at 3500~3800 rpm for 25~30s, and drying at 30~40℃ for 24~30h. The top electrode layer is prepared by placing a glass plate in a vacuum evaporation coating equipment, first depositing a 10-15 nm thick gold foil at a speed of 0.2-0.4 nm / s, and then depositing a 70-90 nm thick gold foil at a speed of 2-5 nm / s.

8. A flexible perovskite solar cell, prepared by the method for preparing a flexible perovskite solar cell according to claim 1, characterized in that, It includes a bottom electrode layer, an electron transport layer, a perovskite layer, a hole transport layer and a top electrode layer stacked sequentially, wherein the bottom electrode layer is made of a PET / ITO substrate and the top electrode layer is made of metal vapor deposition; The perovskite layer comprises the following raw materials in parts by weight: 85.5-87 parts of formamidinium hydroiodate, 250-280 parts of lead iodide, 10-11.5 parts of cesium iodide, 1.5-2 parts of methylammonium bromide, 6-8 parts of methylammonium chloride, 35-38 parts of modified polyurethane solution, and 0.8-1.2 parts of 4-hydrazinobenzenesulfonic acid; the modified polyurethane solution comprises the following raw materials in parts by weight: 18-24 parts of thermoplastic polyurethane, 2-4 parts of 3-isocyanate-propyltriethoxysilane, and 1400-1500 parts of anhydrous N,N-dimethylformamide.

9. A flexible perovskite solar cell according to claim 8, characterized in that, An isolation layer is also spin-coated between the bottom electrode layer and the electron transport layer. The isolation layer comprises the following raw materials in parts by weight: 10-12 parts of polyvinylcarbazole, 4-6 parts of octadecyltrichlorosilane, and 860-880 parts of anhydrous toluene.

10. A flexible perovskite solar cell according to claim 8, characterized in that, The electron transport layer comprises the following raw materials in parts by weight: 10-20 parts of 15wt% SnO2 colloidal dispersion and 30-60 parts of ultrapure water; The hole transport layer comprises the following raw materials in parts by weight: 70-75 parts Spiro-OMeTAD powder, 1100-1200 parts chlorobenzene, 26-30 parts tributyl phosphate, 8-10 parts 520 g / L TFSI-Li solution, and 3-5 parts 400 g / L FK209-Co(Ⅲ)-TFSI solution.

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